The present invention relates to a method for manufacturing an airbag that is employed as a component of an airbag apparatus installed in a vehicle such as a motor vehicle and is deployed and inflated in the vicinity of an occupant to restrain and protect the occupant.
An airbag apparatus is effective for protecting an occupant seated in a seat from an impact applied to a vehicle such as a motor vehicle. Japanese Laid-Open Utility Model Publication No. 5-42001 discloses such an airbag apparatus. The outer shape of the airbag, which is a part of the airbag apparatus, is formed by an airbag main body. As shown in FIG. 25, an airbag main body 151 is formed into a bag-like shape by joining a pair of main body fabric portions 152 to each other along peripheries. The airbag main body 151 includes an inflation portion, which is inflated by inflation gas supplied in response to an impact applied to the vehicle.
The inflation portion has inflation chambers, which are defined by a first partition 153 and second partitions 154 installed to extend between the main body fabric portions 152. Each second partition 154 has a part that extends in a direction intersecting with the first partition (substantially the left-right direction as viewed in FIG. 25) and contacts the first partition 153. The inflation chambers include a first inflation chamber 155, which is supplied with inflation gas from an inflator (not shown), and second inflation chambers 156, which are adjacent to the first inflation chamber 155 with the first partition 153 in between.
The first partition 153 has openings 157, each of which corresponds to one of the second inflation chambers 156. The first inflation chamber 155 is connected to each of the second inflation chambers 156 via the corresponding opening 157. The first partition 153 also has check valves 158, each of which is located at a position corresponding to one of the openings 157. Each check valve 158 permits inflation gas to flow from the first inflation chamber 155 to the corresponding second inflation chamber 156, while restricting inflation gas from flowing back (from the second inflation chamber 156 to the first inflation chamber 155).
The airbag main body 151 has the inflation portion, which is divided into multiple inflation chambers (the first inflation chamber 155 and the second inflation chambers 156) by multiple partitions (the first partition 153 and the second partitions 154), each of which is installed to extend between the main body fabric portions 152. In the airbag main body 151 with such a structure, the way in which the partitions (the first and second partitions 153, 154) are attached to the airbag main body 151 can be a difficult task. Particularly, in the above described publication, each second partition 154 is installed to extend between the main body fabric portions 152, while partly extending in a direction intersecting with the first partition 153 and being attached to the first partition 153. In such an airbag, the attachment of the second partitions 154 is troublesome. However, the publication only recites the structure of the airbag, but fails to describe a method for manufacturing the airbag.
Accordingly, it is an objective of the present invention to provide a method for easily manufacturing an airbag having an inflation portion that is divided into a plurality of inflation chambers by a first partition that is installed to extend between a pair of main body fabric portions and a second partition that is installed to extend between the main body fabric portions while contacting the first partition.
To achieve the foregoing objective and in accordance with one aspect of the present invention, a method for manufacturing an airbag is provided. The airbag is formed into a bag shape by joining peripheral portions of two main body fabric portions and has an inflation portion that is inflated by inflation gas. The airbag includes two structural fabric portions. A first partition is installed to extend between the main body fabric portions. A second partition having an extended end is installed to extend between the main body fabric portions in a state in which the second partition extends in a direction intersecting with the first partition and the extended end is overlaid onto the structural fabric portions. At least a part of the inflation portion is divided into a plurality of inflation chambers by the first partition and the second partition. The airbag manufacturing method includes a first joining step, a second joining step, and a third joining step. In the first joining step, a peripheral portion in each structural fabric portion that is brought closer to the main body fabric portions at the installation is joined to the main body fabric portions in a spread state. In the second joining step, in a pair of outer peripheral portions of the second partition in a spread state, a part that is not overlaid onto the structural fabric portions is joined to the main body fabric portions, and a part that is overlaid onto the structural fabric portions is joined only to the structural fabric portions. In the third joining step, peripheral portions of the structural fabric portions that are separated away from the main body fabric portions at the installation are joined to each other.